If you use Linux on POWER you're forced to use Big Endian mode as the faster Little Endian mode (according to marketting) is reserved for IBM's operating systems.
That's not correct. Ubuntu is LE only and it looks like RHEL is also switching from BE to LE.
"The base RISC-V ISA has a little-endian memory system, but non-standard variants can provide a big-endian..."
Intel added movBE (mov big endian) support in BM2 extension.
Networks are still Big Endian.
SPARC chips (and now RISC-V) are BIG Endian by default.
MIPS just became an independent company a few days ago and they have native Big Endian support.
Edit 1: I was wrong about Power8/9 LE/BE